Complete citation formats for ChatGPT, Claude, Gemini, and other LLMs — plus when you must cite, when disclosure is enough, and the gray areas in between.
AI-generated content is everywhere — in student papers, marketing copy, codebases, and research drafts. But citation standards haven't kept up with adoption. If you used ChatGPT, Claude, or Gemini to help write something, do you cite it? How? And what happens if you don't?
Here's the short answer: if AI contributed ideas, text, or analysis to your work, you must cite it — the same as any other source. The format varies by style guide. Below, we break down exactly how to cite AI output in APA 7th, MLA 9th, and Chicago style, with real examples for each.
The American Psychological Association (APA) updated its guidance in 2024 to explicitly address AI tools. The core rule: treat the AI platform as the author and the model as the title.
Author. (Year). Title of model (Version date) [Large language model]. URL
OpenAI. (2025). ChatGPT (June 5 version) [Large language model]. https://chat.openai.com Anthropic. (2025). Claude (Claude 4 Sonnet) [Large language model]. https://claude.ai Google DeepMind. (2025). Gemini (Gemini 2.0 Pro) [Large language model]. https://gemini.google.com
Parenthetical: (OpenAI, 2025)
Narrative: OpenAI (2025) generated…
Key APA rule: APA treats the AI company as the author — not the model name and not "ChatGPT" alone. Always include the version date and the URL.
The Modern Language Association takes a different approach. Instead of listing the AI as "author," MLA asks you to describe what you did with the tool.
"Description of prompt" prompt. Tool Name, version, Company, Date, URL.
"Explain the photoelectric effect in simple terms" prompt. ChatGPT, June 5 version, OpenAI, 14 Mar. 2025, chat.openai.com. "Summarize the causes of World War I" prompt. Claude, Claude 4 Sonnet, Anthropic, 22 Apr. 2025, claude.ai. "Generate a Python function to sort a dictionary by value" prompt. Gemini, Gemini 2.0 Pro, Google DeepMind, 3 May 2025, gemini.google.com.
MLA also recommends signaling AI use in the body of your text:
When asked to explain the photoelectric effect, ChatGPT described it as "a phenomenon where electrons are emitted from a material when light shines on it."
The Chicago Manual of Style recommends treating AI-generated content like personal communication — cite it in footnotes or endnotes, but do not include it in the bibliography unless a publicly accessible URL exists.
1. Text generated by [Tool Name], [Company], [Date], [URL if available].
1. Text generated by ChatGPT, OpenAI, March 14, 2025, https://chat.openai.com. 2. Text generated by Claude, Anthropic, April 22, 2025, https://claude.ai. 3. Text generated by Gemini, Google DeepMind, May 3, 2025, https://gemini.google.com.
Chicago nuance: If the AI output is accessible via a public URL (as ChatGPT and Claude links are), include it. If the tool requires login and the URL isn't publicly accessible to readers, treat it as personal communication and cite it in the text only.
| Scenario | Requirement | Format |
|---|---|---|
| AI wrote substantial text you included | Must cite | Full citation (APA/MLA/Chicago) |
| AI generated ideas or analysis you used | Must cite | Full citation |
| AI paraphrased a source for you | Must cite | Cite the original source + note AI use |
| AI corrected grammar or spelling | Disclosure only | Methods note or acknowledgments |
| Brainstorming; substantially rewritten | Disclosure recommended | Methods note |
| AI-generated images or code | Must cite | Full citation + license note |
| Style | Author | Title | Bibliography? |
|---|---|---|---|
| APA 7th | Company (OpenAI) | Model name + version | Yes |
| MLA 9th | Prompt description | Tool name | Yes (Works Cited) |
| Chicago | Not applicable | Tool name | No (footnote only) |
Updated June 18, 2026. Citation guidance reflects the latest style manual updates. Always confirm with your institution or publisher for any additional requirements.